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Old 28 September 2016, 10:21   #5
Toni Wilen
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 43
Posts: 20,620
Old thread but Opalvision support is getting closer. Most basic functions have been reverse-engineered during last few days.

- Main control line (the very first PAL or NTSC line) structure is known. Different encoding than other lines for some unknown reason.
- Misc registers, palette and "CoPro" line (next 3 lines) encoding (usual 4-bits per pixel RGBI digital data) is known. Image data also uses same encoding.

I am not sure if I bother with "weird" color modes (BT RAMDAC supports all kinds of rarely used modes, like 8 bit true color) but at least normal paletted and 24-bit mode should be easy enough to emulate.

"This is not that difficult to reverse after all" moment happened when I noticed that Opalvision document's color mode table and some other Opalvision control bits are actually BT RAMDAC features (Harlequin Plus uses same RAMDAC and I had implemented part of it earlier. Timing always matters..) and RAMDAC documentation is very good. (Opalvision documentation of course does not mention it..)

More info later..
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